Vault-light.



UNITED STATES PATENT OEEICE.

ROBERT M. COX, OF PHILADELPHIA, PENNSYLVANIA VAU LT- LIGHT.

SPECIFICATION forming part of Letters Patent No. 656,344, dated August21, 1900.

Application filed July 5, loo.

T0 all whom it may concern:

Be it known that I, ROBERT M. COX, of the city and county ofPhiladelphia and State of Pennsylvania, have invented an Improvement inVault-Lights, of which the following is a specification.

My invention relates to vault-lights and it consist-s of theimprovements which are fully set forth in the following specificationand are shown in the accompanying drawings.

In vault-lights, which as generally used are subjected to considerabletravel and traflic, much difficulty has been experienced owing to theliability of the incident light-transmitting surfaces becoming scratchedand roughened by the feet of pedestrians and the passage of otherobjects. Such scratching and roughening of the incident surfacesseriously impairs the efficiency of the lights.

It is one of the objects of my invention to enable the incident surfacesto be effectively protected from contact with the feet of pedestriansand with other passing objects, so that they may not become scratched orworn and their light-transmitting qualities may not be impaired.

It is also an object of my invention, While accomplishing this result,to improve the foothold afforded by the upper surface of the light, thuspreventing slipping.

It is also an object of my invention to improve the light-transmittingaction of the vault-light, so that by means of lenses the light-rays maybe more effectively changed in direction to suit the particularrequirements in lighting up dark interiors.

Difficulty has also been eXperinced in keeping the vault-lights cleanand free from an accumulation of dust and of mud and dirt collected fromthe feet of pedestrians.

It is also an object of my invention-to provide a vault-light withanupper surface which may easily be Washed and kept clean and in whichthere are no pockets or angles for the lodgment of dirt and dust.

In the drawings, Figure l is a perspective view of a vault-lightembodying my invention. Fig. 2 is a similar view Villustrating anotherform thereof, and Fig. 3 is a transverse vertical section on the line a:of Fig. 2.

Each vault-light consists of a unitary piece of glass or translucentmaterial adapted to be Serial No. 22.493. (No model.)

placed singly or in combination with others in a suitable frame, as isnow well known in the art. The light consists of a single prism a ofsuitable size and prismatic angle to suit the conditions, arranged uponthe underside and depending from a horizontal top b, the side edges ofwhich preferably project laterally beyond the top of the prism and theupper surface of which is provided with a series of concave grooves c,forming with their meeting edges a series of more or less sharp angularridges d. These grooves c and the ridges cl formed by them are of muchless size than the single prism a, so that each light has a singlerelatively-large and extended prism on the lower side and a series ofrelativelysmall concave lenses and angular ribs on the upper or incidentside. These grooves c and ribs d may be arranged either transversely tothe direction of the prism c, as shown in Fig. 1, or parallel thereto,as in Figs. 2 and 3, and in other cases, when the conditions render itexpedient, they may be arranged diagonally to the direction of theprism. As the effective incident surfaces afforded by the top b of lightare the concave lenses c, and as these concavaties are of small width,they will be effectively protected from contact with the feet ofpedestrians and objects passing over them, which will make contact onlywith the raised angular ribs or ridgesd, and consequently therefracting-lense surfaces c will not become scratched and worn, andtheir light-transmitting efficiency will not be im- Ypaired by traveland traffic. Not only do the angular projecting ribs b thus serve toprotect the incident light-transmitting surfaces c from contact withobjects passing over them, but they also serve the purpose of preventinga rmer foothold for pedestrians and prevent slipping. Another advantageof this surface construction of my improved vault-light is the facilitywith which it may be washed and kept clean. The concave grooves formgutters through which the mud and dust may be readily carried away, andthere are no small recesses or grooves forming pocket-s in whichparticles of dust and dirt may become lodged.

The eect of the prism in refracting the light passing through it is wellunderstood, and the concave lenses perform the further loo l well-knownfunction ot' a lense of producing an additional angular deviation of thelightrays, so that the emergent rays are more Widely spread out, andconsequently the dark interiors may be effectively illuminated. Bychanging the angular disposition of the lenses and ribs relatively tothe prism u. this extra angular deviation produced by the lenses may beobtained in any desired direction to suit the special requirement of theinterior space to be illuminated.

The details of construction mai,7 be varied Without departing from theinvention.

XVhat I claim as new, and desire to secure by Letters Patent, is asfollows:

l. A vault-light of translucent material, consisting ota singleelongated prism depending from a [lat top portion which is provided witha series of relatively-small concave grooves meeting in a series ofangular ribs, said ribs presenting a ronghened foot-sur- ;l'ace andprotecting the faces of the concave grooves from contact with the feetof pedestrians.

2. A vault-light of translucent material,

consisting of a single elongated prism depending trom a ilat top portionwhich provided with a series oi relatively -small concave grooves extending atan angle to the direction ofthe single depending prism and meetingin a series of angular ribs, said ribs presenting a roughened[foot-surface and protecting the faces of the concave grooves fromcontact with the feet of pedestrians.

3. A vault-light of translucent material, consisting of alight-refracting portion depending irom a flat top portion which isprovided with a series of relatively-small concave grooves meeting in aseries of angularribs, said ribs presenting a roughened footsurface andprotecting the faces of the concave grooves from contact with the feetof pedestrians.

In testimony ot` which invention I have hereunto sot my hand.

.Vitnesses:

Gnonon l. Gnoscn, Clins. M. WAGNER.

